Patrick O'Brien in a Spiderman wind suit jogs around Lake Harriet in south Minneapolis, Minnesota, USA. A blast of Arctic air gripped the mid-section of the U.S., bringing the coldest temperatures in two decades, forcing businesses and schools to close and causing widespread airline delays and hazardous driving conditions.

German Chancellor Angela Merkel uses crutches as she attends the annual reception for Carolers at the chancellery in Berlin. Merkel suffered a pelvis injury during ski holidays in the Swiss Alps and will have to cut back on her work schedule for the next three weeks.